Leadless pacemaker with end-of-life protection

ABSTRACT

An implantable medical device includes operational circuitry, such as a therapy circuit. The implantable medical device also includes a power source configured to deliver energy to the operational circuitry, and a deactivation element configured to disable the therapy circuit. A power manager is configured to detect an end-of-life condition of the power source and, in response to detecting the end-of-life condition, cause the deactivation element to reversibly disable the therapy circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Provisional Application Nos.61/919,572; 61/919,575; and 61/919,567, all of which were filed on Dec.20, 2013, and each of which is herein incorporated by reference in itsentirety.

TECHNICAL FIELD

The present invention relates to an implantable system having animplantable medical device. More specifically, the invention relates tomanaging and and-of-life condition associated with an implantablemedical device.

BACKGROUND

Implantable medical devices include, among other things, cardiac rhythmmanagement (CRM) devices such as pacers, cardioverters, defibrillators,cardiac resynchronization therapy (CRT) devices, leadless pacing seeds,as well as combination devices that provide more than one of thesetherapy modalities to a subject. Such implantable devices are typicallypowered by a battery. As the battery's useful life becomes exhausted,the implanted device may malfunction, causing errors in the therapy itprovides and/or its communication with other devices.

SUMMARY

In Example 1, the present disclosure describes an implantable medicaldevice comprising operational circuitry, wherein the operationalcircuitry comprises at least one of a therapy circuit and a sensorcircuit. The implantable medical device also includes a communicationsmodule, a power source configured to deliver energy to the operationalcircuitry, and a deactivation element configured to at least partiallydisable the operational circuitry by interrupting delivery of energyfrom the power source to the operational circuitry. A power managerdisposed within the specification is configured to detect an end-of-lifecondition of the power source and, in response to detecting theend-of-life condition, cause the deactivation element to at leastpartially reversibly disable the operational circuitry.

In Example 2, the implantable medical device of Example 1, wherein theimplantable medical device comprises a leadless cardiac pacing seed.

In Example 3, the implantable medical device of Example 1, wherein theoperational circuitry comprises the therapy circuit.

In Example 4, the implantable medical device of Example 3, wherein thedeactivation element is configured to prevent energy from beingdelivered to the therapy circuit.

In Example 5, the implantable medical device of Example 1, furthercomprising a memory component configured to store an indication of apost end-of-life state of the implantable medical device.

In Example 6, the implantable medical device of Example 5, wherein thememory component comprises an active storage element.

In Example 7, the implantable medical device of Example 6, wherein thepower manager is configured to allow energy to be delivered to thememory component during the end-of-life state.

In Example 8, the implantable medical device of Example 5, wherein thememory component comprises a non-volatile memory element.

In Example 9, the implantable medical device of Example 9, wherein thememory component is further configured to store a plurality ofoperational parameters during the end-of-life state.

In Example 10, the implantable medical device of Example 10, wherein thepower source comprises a rechargeable battery.

In Example 11, the implantable medical device of Example 11, furthercomprising a controller, wherein the controller is configured to accessthe plurality of operational parameters in response to receiving anactivation signal.

In Example 12, the implantable medical device of Example 11, wherein thecontroller is configured to restore the device to its pre-end-of-lifestate using the operational parameters.

In Example 13, the present disclosure describes a leadless cardiacpacing seed comprising a therapy circuit, a communications module, and apower source configured to deliver energy to the therapy circuit and thecommunications module. The leadless cardiac pacing seed also includes adeactivation element configured to disable at least one of the therapycircuit and the communications module by reversibly interruptingdelivery of energy from the power source to the therapy circuit or thecommunications module. A power manager disposed within the leadlesscardiac pacing seed is configured to detect an end-of-life condition ofthe seed and, in response to detecting the end-of-life condition, causethe deactivation element to reversibly disable at least one of thetherapy circuit and the communications module.

In Example 14, the leadless cardiac pacing seed of Example 13, furthercomprising a memory component configured to store an indication of anend-of-life state.

In Example 15, the leadless cardiac pacing seed of Example 14, whereinthe memory component comprises an active storage element.

In Example 16, the leadless cardiac pacing seed of Example 15, whereinthe power manager is configured to allow energy to be delivered to thememory component during the end-of-life state.

In Example 17, the leadless cardiac pacing seed of Example 14, whereinthe memory component comprises a non-volatile memory element.

In Example 18, the leadless cardiac pacing seed of Example 17, whereinthe memory component is further configured to store a plurality ofoperational parameters during the end-of-life state, and wherein thecontroller is configured to access the plurality of operationalparameters in response to receiving an activation signal.

In Example 19, the leadless cardiac pacing seed of Example 18, whereinthe controller is configured to restore the device to itspre-end-of-life state using the operational parameters.

In Example 20, the present disclosure describes a cardiac pacing systemcomprising an implantable leadless cardiac pacing seed configured todeliver electrostimulation therapy to a patient and an external device.The implantable leadless cardiac pacing seed includes a therapy circuit,a communications module configured to receive a deactivation signal fromthe external device, and a power source configured to deliver energy tothe therapy circuit and the communications module. A power manager isconfigured to detect an end-of-life condition of at least one of thepower source and the therapy circuit and, in response to detecting theend-of-life condition, place the implantable leadless cardiac pacingseed in an end-of-life state. The implantable leadless cardiac pacingseed also includes a deactivation element configured to interruptdelivery of energy from the power source to the therapy circuit so as toreversibly disable the therapy circuit in response to the deactivationsignal being received by the communications module. Additionally, theleadless cardiac pacing seed includes a memory component configured tostore an indication of an end-of-life state of the seed.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an implantable system having aleadless implantable stimulator and a control device in an implantedstate, in accordance with embodiments of the invention;

FIG. 2 is a schematic block diagram of an implantable system having anIMD and a control device, in accordance with embodiments of theinvention;

FIG. 3 is a schematic block diagram of an IMD, in accordance withembodiments of the invention;

FIG. 4 is a flow diagram depicting an illustrative method of managing anend-of-life state of an IMD, in accordance with embodiments of theinvention;

FIG. 5 is another flow diagram depicting an illustrative method ofmanaging an end-of-life state of an IMD, in accordance with embodimentsof the invention;

FIG. 6 is a schematic block diagram of an IMD, in accordance withembodiments of the invention;

FIG. 7 is a schematic block diagram of an IMD, in accordance withembodiments of the invention;

FIG. 8 is a flow diagram depicting an illustrative method ofdeactivating an IMD, in accordance with embodiments of the invention;

FIG. 9 is another flow diagram depicting an illustrative method ofdeactivating an IMD, in accordance with embodiments of the invention;

FIG. 10 is a schematic block diagram depicting an illustrativeimplantable leadless pacing system, in accordance with embodiments ofthe invention;

FIG. 11 is a flow diagram depicting in illustrative method of replacinga first IMD with a second IMD;

FIG. 12 is a flow diagram depicting an illustrative method of mitigatingthe effects from a loss of a leadless pacing seed, in accordance withembodiments of the invention;

FIG. 13 is a schematic circuit diagram depicting an illustrative circuitarrangement for an implantable medical device, in accordance withembodiments of the invention; and

FIG. 14 is another schematic circuit diagram depicting an illustrativecircuit arrangement for an implantable medical device, in accordancewith embodiments of the invention.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of an implantable system 100including an implantable medical device (IMD) 102 implanted within achamber of a patient's heart 104. In the embodiment illustrated in FIG.1, the IMD 102 is a wireless electrode stimulator assembly, referred toherein, interchangeably, as a “seed.” The system 100 also includes aco-implanted device 106 that is configured to communicate with the seed102. In various embodiments, the co-implanted device 106 can beimplanted subcutaneously within an implantation location or pocket inthe patient's chest or abdomen. The co-implanted device 106 may be animplantable medical device known in the art or later developed, fordelivering an electrical therapeutic stimulus to the patient. In variousembodiments, the co-implanted device 106 may provide therapy and/ordiagnostic data about the patient and/or the co-implanted device 106. Invarious embodiments, the co-implanted device 106 may be a communicationrepeater for extra-corporeal communication to external device 108. Invarious embodiments, the co-implanted device 106 may be a pacemaker, animplantable cardioverter defibrillator (ICD) device, or a cardiacresynchronization therapy (CRT) device. In various embodiments, theimplantable control device 106 may include both defibrillation andpacing/CRT capabilities (e.g., a CRT-D device).

In embodiments, the co-implanted device 106 includes circuitry to senseand analyze the heart's electrical activity, and to determine if andwhen a pacing electrical pulse needs to be delivered and, in embodimentshaving multiple seeds 102, by which of the seeds 102 the pulse should bedelivered. The sensing capability may be made possible by having senseelectrodes included within the physical assembly of the co-implanteddevice 106. Alternatively, a conventional single or dual lead pacemaker(not shown in FIG. 1) may sense the local cardiac electrocardiogram(ECG) and transmit this information to the co-implanted device 106 foruse in determination of the timing of seed firing. In embodiments, theseed 102 may include sensing capability, and may communicate sensedinformation to other seeds 102 and/or to the co-implanted device 106. Inembodiments, the co-implanted device 106 may transmit charge energy anddata, such as pace trigger signals, pacing amplitude information, andpulse width information to the seed 102 via radio-frequency (RF)communications, acoustic communications, inductive communications,electrical communications, microwave communications, conductivecommunications, and/or the like.

In the embodiment shown in FIG. 1, the seed 102 is implanted in theright ventricle 110. The seed 102 may sense electrical signals of theheart 104 and/or deliver electrical pulses to the heart 104 in anattempt to correct an arrhythmia and restore sinus rhythm. In otherembodiments, the seed 102 may be implanted or placed within any chamberof the heart 104. For example, the seed 102 may be implanted in theright atrium 112, the left ventricle 114, or the left atrium 116. Inaddition, the seed 102 may be implanted into or be placed on theepicardium 118, for example the epicardium 118 of the right ventricle110, the right atrium 112, the left ventricle 114 or the left atrium116. In such cases, the seed 102 can be delivered through thecirculatory system of the heart 104 to the location of interest, or itcan be implanted or placed on the epicardium 118 by gaining access tothe pericardial space. In some embodiments, the seed 102 may beimplanted through the epicardium 118 or endocardium 120 and into themyocardium 122. In other embodiments, the system 100 may include aplurality of seeds 102, each placed in, implanted in, or attached to adifferent chamber or a different part of the heart 104.

In embodiments, implantable systems such as implantable system 100 maybe unipolar, multipolar (e.g., bipolar, quad-polar, etc.) orconfigurable such that a unipolar or multipolar operation can beselected. In a unipolar system, an electrode of the seed 102 acts as onepole of an electrical system, and the second pole of the electricalsystem may be located remotely from the electrode. For example, thesecond pole of the electrical system may be located on the housing ofthe seed 102 or on a wire connected to the seed 102. Various otherconfigurations for unipolar devices are known in the art.

In a bipolar system, the implantable system 100 may have two or moreelectrodes disposed near the site of treatment. For example, a seed 102may have two electrodes disposed on the body of the seed 102 (e.g., atip electrode and a ring electrode). The two electrodes may act as thetwo electrical poles of the seed 102. Various other configurations forbipolar electrodes are known in the art. According to embodiments, theelectrodes of the seeds 102 also may be configured to sense certainphysiological attributes of the heart 104. For example, the heart's 104natural electrical signals can be received by an electrode andtransmitted to a remote location (e.g., the co-implanted device 106). Inaddition, other sensing mechanisms that are known in the art may beplaced within, on or near the seeds 102, and may include, for example,pressure sensors, motion sensors, and/or the like. Although the seed102, and corresponding system 100, illustrated in FIG. 1 is configuredfor cardiac therapy, other implantable seed applications, such as thoseconfigured for neurostimulation, e.g., Spinal Cord Stimulation (SCS),Deep Brain Stimulation (DBS), and Functional Electrical Stimulation(FES), also are contemplated within the scope of various embodiments.

In embodiments, the seed 102 has an internal receiver that may receivecommunications and/or energy from co-implanted device 106, which mayinclude a transmitter. The co-implanted device 106 may include a pulsegenerator that supplies an appropriate time-varying energy (e.g.,current or voltage) to the seed 102. The seed 102 may include a powersource for storing electrical energy, and may also have a triggeringmechanism to deliver stored electrical energy to adjacent heart tissue.

FIG. 2 is a block schematic diagram of a system including an IMD 200(such as, for example, the seed 102 depicted in FIG. 1) and aco-implanted device 202. As illustrated in FIG. 2, the IMD 200 includesa power component 204 that provides electrical energy to a set 206 ofcomponents. The set 206 of components include a controller 208, a memory210, a communications component 212, a therapy circuit 214, and a powermanager 216. As shown in FIG. 2, the therapy circuit 214 is coupled toelectrodes 218 and 219 and is configured to provide stimulation energyto the electrodes, which, in turn, provides the energy to a patient'sbody (e.g., a location in a patient's heart). According to embodiments,the IMD 200 may include more than two electrodes. The power component204 includes a power source 220 configured to store electrical energyand a deactivation element 222 configured to prevent, upon itsactivation, energy from being delivered to one or more components (e.g.,the controller 208, the communications component 212, the therapycircuit 214) of the IMD 200. According to embodiments, the power source220 may include one or more batteries, capacitors, and/or the like. Inembodiments, the IMD 200 may include other components such as, forexample, one or more sensor circuits (not shown), coupled to one or moresensors and/or the electrodes 218 and 219, for sensing physiologicalparameters.

According to embodiments, the power manager 216 may be configured todetect an end-of-life (EOL) condition associated with the IMD 200. Inembodiments, the power manager 216 may detect an EOL condition bydetermining that the capacity of the power source has been depletedbelow a predetermined threshold (e.g., 10% of total capacity), that theoperation of one or more components (e.g., the controller 208, thetherapy circuit 214, and/or the communications component 212) appears tobe altered due to a deficiency of energy being delivered from the powersource 220, and/or the like. In embodiments, the power manager 216 maymonitor the operation of various components of the IMD 200 by accessingdata from the controller 208. In other embodiments, the power manager216 may monitor the operation of components directly.

According to various embodiments, the deactivation element 222 maycomprise one or more elements, circuits, logical components, and/or thelike, and may be configured to prevent electrical energy from beingdelivered from the power source 220 or to one or more components of theIMD 200. In embodiments, for example, the deactivation element 222 maybe, or include, a short-circuit element (e.g., a fuse), a switch (e.g.,a field-effect-transistor (FET) fuse), a crowbar mechanism, and/or thelike. The deactivation element 222 may be configured to selectivelyprevent electrical energy from being delivered to certain components ofthe IMD 200 and, in embodiments, the deactivation element 222 may beconfigured to prevent electrical energy from being delivered to all ofthe components of the IMD 200. The deactivation element 222 may, inembodiments, be configured to permanently and/or reversibly preventelectrical energy from being delivered to one or more components of theIMD 200. In embodiments, the power manager 216 may control the operationof the deactivation element 222.

The deactivation element 222, which may include one or more circuitelements that require electric energy to function, may be powered by thepower source. For example, as indicated above, the deactivation element222 may include a fuse that, blows upon being provided with apredetermined amount of energy, thereby permanently preventingelectrical energy from being provided to one or more of the componentsof the IMD 200. This energy may be provided by the power source 220, inresponse to a signal from the power manager 216. In other embodiments,the deactivation element 222 may include a switch that requires energyto be activated, which may be provided by the power source 220. In theseand other implementations, as the power source 220 becomes depleted, itmay reach a condition in which it does not include enough power toactivate the deactivation element 222. According to embodiments, apredetermined amount, or range, of energy may be sequestered for use inactivating the deactivation element 222.

The co-implanted device 202 includes a communications component 224having circuits and one or more transmitters and/or receivers forcommunicating wirelessly with the seed 200. The communications component212 of the IMD 200 includes a transceiver 226 and an antenna 228 (ormultiple antennae) that work together to facilitate wirelesscommunication 230 with the co-implanted device 202, which may includeone or more implantable co-implanted devices (e.g., the co-implanteddevice 106 depicted in FIG. 1) and/or an external device (e.g., theexternal device 108 depicted in FIG. 1). In embodiments, thecommunications component 212 may also facilitate communications withother IMDs 200 (e.g., other seeds) such as, for example, to facilitatecoordinated operations between the IMDs. According to variousembodiments, the communications component 212 may include one or moretransmitters, receivers, transceivers, transducers, and/or the like, andmay be configured to facilitate any number of different types ofwireless communication such as, for example, radio-frequency (RF)communication, microwave communication, infrared communication, acousticcommunication, inductive communication, conductive communication, and/orthe like. The communications component 224 may, in addition tofacilitating wireless (e.g., RF, microwave, acoustic, etc.)communication with the IMD 200, facilitate wireless communication withan external device (e.g., the external device 130 depicted in FIG. 1),such as a programming device, such that information may be provided tothe co-implanted device 202 or supplied to the external device. Inembodiments, the communications component 224 may include an antennadisposed on or in the co-implanted device 202 or on a distal portion ofan attached lead (not shown).

In an implementation, the co-implanted device 202 includes a controller232 that may include, for example, a processing unit, a pulse generator,and/or the like. The controller 232 may be a programmablemicro-controller or microprocessor, and may include one or moreprogrammable logic devices (PLDs) or application specific integratedcircuits (ASICs). The controller 232 may execute instructions andperform desired tasks as specified by the instructions. The controllermay also be configured to store information in the memory 234 and/oraccess information from the memory 234. The memory 234 may includevolatile and/or non-volatile memory, and may store instructions that,when executed by the controller 232 cause methods and processes to beperformed by the co-implanted device 202. For example, in embodiments,the controller 232 may process instructions and/or data stored in thememory 234 to control delivery of an electrical stimulation therapy bythe IMD 200. Additionally, the co-implanted device 202 may sensephysiological parameters and/or deliver therapy using a sensor/therapycircuit 236 that may be coupled, for example, to electrodes 238 and 239,a sensor (not shown), or a combination of these. In embodiments, thesensor/therapy circuit 236 may actually include multiple circuits. Thememory 234 may be used to store pacing parameters and sensed informationaccording to some implementations. The co-implanted device 202 may alsoinclude a power source (e.g., a battery) (not shown) that supplies powerto the circuits and components of the co-implanted device 202. In someimplementations, the controller 232 may include memory as well. Althoughthe present system is described in conjunction with a co-implanteddevice 202 having a microprocessor-based architecture, it will beunderstood that the co-implanted device 202 (or other device) may beimplemented in any logic-based integrated circuit architecture, ifdesired.

The controller 232 may include digital-to-analog (D/A) converters,analog-to-digital (ND) converters, timers, counters, filters, switches,etc. (not shown). The controller 232, sensor/therapy circuit 236 (e.g.,sensing circuits), memory 234, and communications component 224 may worktogether to control communication between the co-implanted device 202and one or more leadless electrode assemblies (e.g., IMD 200) tofacilitate providing pacing stimuli to the heart. In an implementation,the controller 232 may encode information, such as a unique identifier,pacing threshold information, pulse width information, pacing triggersignals, demand pacing information, pace timing information, and thelike, to be transmitted to the seed 200.

Information from sense circuits included in the sensor/therapy circuit236 may be used to adjust pacing or communications parameters. The sensecircuits may amplify and filter signals sensed from sensors positionedin the right or left atrium, or in the right or left ventricle, or fromsensors on an external surface of the pacing controller. As isconventional, the sense circuits may include one or more ND converters.The sensors may be attached to leads implanted within, on, or near theheart, and in some implementations the seed 200 may include sensors andmay transmit sensed information to the co-implanted device 202 directlyor through a lead that includes a receiver. In some implementations, theseed electrodes that deliver pacing energy to the tissue are the same asthe sense electrodes used to sense the local electrical voltage at thepacing site. In these cases, sensing may be paused when pacing energy isbeing delivered. Similarly, the transmitter/receiver that receivescommunications may be the same as the transmitter/receiver that sendssensed information back to the co-implanted device 202, according tosome implementations. In these cases, outgoing transmissions may bepaused when communications are being received. The sensor/therapycircuit 236 of the co-implanted device 202 may include, for example, oneor more can or housing electrodes disposed on an exterior surface of theco-implanted device 202.

In embodiments, for example, the controller 232 may receive, via thecommunications component 224, an indication of an EOL conditioncorresponding to an IMD 200, which the controller 232 may store in thememory 234. Based on the indication of the EOL condition of the IMD 200,the controller 232 may determine a modified therapy program and/orcommunication structure associated with additional IMDs and provide, viathe communications component 224, operational parameters correspondingto the new program and/or structure to the additional IMDs, an externaldevice, and/or the like. In this manner, therapy programs andcommunication structures may be modified to compensate for the loss ofan IMD 200 such as, for example, when the power source of an IMD 200depletes such that the IMD 200 reaches an EOL condition.

The illustrative IMD 200 and co-implanted device 202 shown in FIG. 2 arenot intended to suggest any limitation as to the scope of use orfunctionality of embodiments of the invention disclosed throughout thisdocument. Neither should the illustrative IMD 200 and co-implanteddevice 202 be interpreted as having any dependency or requirementrelated to any single component or combination of components illustratedtherein. For example, in embodiments, the illustrative IMD 200 mayinclude additional components such as, for example, a sensor circuit(not illustrated). Additionally, any one or more of the componentsdepicted in FIG. 2 can be, in embodiments, integrated with various onesof the other components depicted therein (and/or components notillustrated). Any number of other components or combinations ofcomponents can be integrated with the illustrative IMD 200 and/orco-implanted device 202 depicted in FIG. 2, all of which are consideredto be within the scope of this disclosure.

FIG. 3 is a schematic block diagram of an IMD 300 illustrating aspectsof embodiments of the invention. As shown in FIG. 3, the IMD 300includes a power component 302 that powers operational circuitry 304 ofthe IMD 300. The operational circuitry 304 includes a controller 306coupled to a memory 308. An oscillator 310 coupled to the controller 306may be used as a clocking mechanism to provide timing functions to thecontroller 306. In embodiments, other types of clocking mechanisms maybe used as well as, or in addition, to the oscillator 310. Theoperational circuitry 304 also includes a communications component 312,a therapy circuit 314, and a power manager 316. As shown in FIG. 3, thetherapy circuit 314 is coupled to electrodes 318 and 319 and isconfigured to provide stimulation energy to the electrodes, which, inturn, provide the energy to a patient's body (e.g., a location in apatient's heart). According to embodiments, the IMD 300 may include morethan two electrodes. Additionally, the communications component 312 maybe similar to the communications component 212 depicted in FIG. 2 andinclude a transceiver and an antenna. In embodiments, any number of thecomponents illustrated in FIG. 3 may be, include, or be similar to,similarly named components depicted in FIG. 2. The IMD 300 may includeany number of additional components as well such as, for example, asensor circuit.

As shown in FIG. 3, the power component 302 includes a power source 320coupled to a deactivation element 322. The illustrated power source 320includes a first energy storage component 324 and a second energystorage component 326. According to embodiments, the first energystorage component 324 may include, for example, a battery, and may beconfigured to provide electrical energy to any one or more of theoperational circuitry 304 of the IMD 300. The second energy storagecomponent 326 may include, for example, a capacitor and/or an additionalbattery, and may be configured to store a predetermined amount, orrange, of electrical energy for activating the deactivation element 322.In embodiments, for example, when the power manager 316 detects that anend-of-life (EOL) condition of the IMD 300 is nearing, the power manager316 may send a signal to the power source 320 to cause a predeterminedamount, or range, of electrical energy to be transferred from the firstenergy storage component 324 to the second energy storage component 326,which may store the energy until receiving a signal from the powermanager 316 that causes the second energy storage component 326 toprovide at least a portion of the stored electrical energy to thedeactivation element 322, thereby activating the deactivation element322.

In embodiments, the power manager 316 may be configured to enter apre-EOL state in which it is configured to cause deactivation only uponthe satisfaction of a trigger condition. In embodiments, for example,the trigger condition may include detecting that the first energystorage component 324 has depleted beyond a predetermined threshold;detecting an abnormality or interruption in the functionality of thetherapy circuit 314, the communications component 312, the controller306, and/or the oscillator 310; receiving a signal from a deviceexternal to the IMD 300 (e.g., another IMD, a control device, anexternal programmer, an external magnet, and/or the like); determiningthat a certain event has not occurred (e.g., determining that apredetermined signal has not been received within the passage of acertain amount of time); and/or the like.

Upon detecting the occurrence of the trigger condition, the powermanager 316 may send a signal to the power component to cause the energystored in the second energy storage component 326 to be provided to thedeactivation element 322, which may be electronically, logically, and/orcommunicatively coupled to any one or more of the components of theoperational circuitry 304 of the IMD 300. In embodiments, the transferof energy to the deactivation element 322 may cause the deactivationelement 322 to enter an EOL state, in which the deactivation element 322prevents electrical energy from being delivered to one or morecomponents of the IMD 300. For example, the deactivation element 322 mayinclude a fuse or switch that interrupts a conduction path between thefirst energy storage component 324 and the therapy circuit 314, thecommunications component 312, the controller 306, and/or the oscillator310. In embodiments, the deactivation element 322 may include aparasitic circuit that further depletes the first energy storagecomponent 324 such as, for example, a crowbar mechanism. A crowbarmechanism may include any number of different types of circuitsconfigured to drain energy from the first energy storage component 324,thereby preventing delivery of energy from the first energy storagecomponent 324 to any other component.

FIGS. 13 and 14 are schematic circuit diagrams depicting illustrativeexamples of crowbar mechanisms that may, in embodiments, be utilized asa deactivation element 322. FIG. 13 depicts a bipolar circuitarrangement in which a power source 1302 (e.g., a battery) provideselectrical power (e.g., via current) to operational circuitry 1304(e.g., the operational circuitry 304 depicted in FIG. 3). A crowbarmechanism 1306 is disposed between the power source 1302 and theoperational circuitry 1304 and may be utilized as a deactivation element(e.g., the deactivation element 322 depicted in FIG. 3) to prevent powerfrom being delivered to the operational circuitry 1304. A triggerconnection 1308 is used to provide a trigger signal (e.g., adeactivation signal) to a first (NPN) transistor T1. The trigger signalactivates T1, which causes a second (PNP) transistor T2 to activate,thereby draining power from the power source 1302. The crowbar mechanism1306 may be, or include, a traditional silicone-controlled rectifier(SCR), discrete transistors T1 and T2, or the like. The resistor R1,illustrated in FIG. 13, may be selected to allow rapid depletion of thepower source 1302 without allowing depletion that is so rapid that itcauses excessive heat. Additionally, R1 may be selected so that theemitter of T2 does not drop to a voltage so low as to prevent T1 and T2from remaining activated. FIG. 14 depicts a circuit arrangement in whicha power source 1402 provides electrical power (e.g., via voltage) tooperational circuitry 1404. A crowbar mechanism 1406 is disposed betweenthe power source 1402 and the operational circuitry 1404 and may beutilized as a deactivation element (e.g., the deactivation element 322depicted in FIG. 3) to prevent power from being delivered to theoperational circuitry 1404. The crowbar mechanism 1406 similar to thatof FIG. 13; however, in FIGS. 14, T1 and T2 aremetal-oxide-semiconductor field-effect transistors (MOSFETs).

Returning to FIG. 3, the IMD 300 may include a rechargeable power source320 such as, for example, a rechargeable battery. In suchimplementations, the IMD 300 may be configured to be partially orcompletely disabled reversibly and then reactivated after the powersource 320 has been recharged. To facilitate returning to a particularoperational state upon reactivation, the controller 306 may beconfigured to save one or more operational parameters associated withthe IMD 300, which may be accessed upon reactivation. The one or moreoperational parameters may be stored in the memory 308. The memory 308may include one or more memory elements such as, for example, anon-volatile memory element, an active memory element, and/or the like.In embodiments, the controller 306 may be configured to store only anindication of an EOL state associated with the IMD 300, while in otherembodiments, the controller 306 may be configured to store a number ofoperational parameters.

Non-volatile memory may be used, for example, to store information evenwhen IMD 300 is completely disabled (e.g., energy is prevented frombeing delivered to every component of the IMD 300). Active memoryelements may be used to store information when the power source 320maintains an ability to provide some energy during the EOL state of theIMD 300. For example, the first or second energy storage component324,326 may include enough stored energy to provide to the memory 308.In embodiments, the memory 308 may be an active storage elementconfigured to store an indication of an EOL state of the IMD 300. Theindication may include a single bit or multiple bits. In the case of asingle bit (or a small number of bits), the memory 308 may include alatch or system of latches. Other techniques for maintaining informationassociated with an EOL state are contemplated within the scope ofembodiments of the invention. For example, in embodiments, upondetecting an EOL condition, the power manager 316 may be configured tocause the IMD 300 to transfer data (e.g., operational parameters,indications of the EOL condition, etc.) to another IMD 300, a controldevice, an external programmer and/or the like.

FIG. 4 is a flow diagram depicting an illustrative method 400 ofmanaging an end-of-life (EOL) state of an IMD, in accordance withembodiments of the invention. The IMD may be, or include, the IMD 102depicted in FIG. 1, the IMD 200 depicted in FIG. 2, and/or the like. Inembodiments, the IMD may be a leadless cardiac pacing seed. As shown inFIG. 4, the illustrative method 400 includes detecting an end-of-life(EOL) condition of the IMD (block 402) and, in response, storing anindication of the EOL condition in a memory (block 404). The method 400also includes configuring a power-up procedure of the IMD such that,when a future activation of the IMD is attempted, the controller firstreads the memory containing the indication of the EOL condition (block406). As depicted in FIG. 4, the IMD is disabled (e.g., by preventingpower from being delivered from a power source to one or more componentsof the operational circuitry of the IMD) (block 408). At some pointlater, the IMD receives an instruction to power up (e.g., an activationsignal) (block 410) and, in response, reads the indication of the EOLstate from the memory (block 412). Upon discovering that the IMD hasbeen placed in the EOL state, the controller terminates the power-upprocedure (block 414).

FIG. 5 is another flow diagram depicting an illustrative method 500 ofmanaging an EOL state of an IMD, in accordance with embodiments of theinvention. According to embodiments, the illustrative method 500includes detecting an EOL condition of the IMD (block 502) and, inresponse, storing a set of parameters in a memory (block 504). Themethod 500 also includes configuring a power-up procedure such that,when a future activation of the IMD is attempted, the controller readsthe parameters from the memory (block 506). The IMD is disabled (e.g.,by preventing power from being delivered from a power source to one ormore components of the operational circuitry of the IMD) (block 508). Atsome point later, the IMD receives an instruction to power up (block510) and, in response, reads the stored set of parameters from thememory (block 512). As shown, the device configures itself for operationbased on the stored parameters (block 514).

As described above, embodiments of the invention include a deactivationelement that facilitates deactivating one or more components of an IMD.The deactivation element may, in embodiments, be configured toselectively disable certain components of an IMD, while allowing othercomponents to remain active. In embodiments, the deactivation elementmay selectively disable components by preventing power from beingdelivered, by the power source, to the selected components. This may beaccomplished by using a deactivation element that includes, for example,a number of switches, latches, gates, and/or the like.

FIG. 6 is a schematic block diagram depicting an illustrative IMD 600having a deactivation element 602 capable of selectively disablingcomponents of the IMD 600, in accordance with embodiments of theinvention. The IMD 600 may include any number of different types of IMDssuch as for example, implantable sensors, implantable stimulators (e.g.,leadless cardiac pacing seeds), implantable control devices, and/or thelike. As shown in FIG. 6, the deactivation element 602 is electricallycoupled to a power source 604 and provides selectable current paths to acontroller 606, a therapy circuit 608, a sensor circuit 610, a memory612, an oscillator 614, and a communications component 616. A powermanager 618 may be configured to monitor the power source 604 and/or oneor more other components to detect an end-of-life (EOL) condition. Inthe illustrated embodiment, the power manager 618 monitors componentssuch as the therapy circuit 608, the sensor circuit 610, and thecommunications component 616 by accessing information from thecontroller 606 corresponding to the operation of those components. Inembodiments, the power manager 618 may include a direct connection tothe components that it monitors.

The illustrative IMD 600 shown in FIG. 6 is not intended to suggest anylimitation as to the scope of use or functionality of embodiments of theinvention disclosed throughout this document. Neither should theillustrative IMD 600 be interpreted as having any dependency orrequirement related to any single component or combination of componentsillustrated therein. For example, in embodiments, the illustrative IMD600 may include additional components such as, for example, additionalsensor circuits (not illustrated). Additionally, any one or more of thecomponents depicted in FIG. 6 can be, in embodiments, integrated withvarious ones of the other components depicted therein (and/or componentsnot illustrated). Any number of other components or combinations ofcomponents can be integrated with the illustrative IMD 600 depicted inFIG. 6, all of which are considered to be within the scope of thisdisclosure.

In an example embodiment, the power manager 618 may monitor the therapycircuit 608 and detect an EOL condition. The EOL condition may include,for example, a condition in which the therapy circuit 608 is deliveringerratic or otherwise unexpected therapy. Upon detecting the EOLcondition, the power manager 618 may send a signal to the deactivationelement 602 to cause the deactivation element 602 to prevent power frombeing delivered from the power source 604 to the therapy circuit 608.The deactivation element 602 may continue to allow power to flow,however, to any number of the other components of the IMD 600. As thepower source 604 continues to deplete, the power manager 618 may detectanother EOL condition by detecting erratic or otherwise unexpectedbehavior by the communications component 616. Upon detecting the EOLcondition, the power manager 618 may send a signal to the deactivationelement 602 to cause the deactivation element 602 to prevent power frombeing delivered from the power source 604 to the communicationscomponent 616.

In embodiments, the deactivation element may selectively disablecomponents by logically disabling the selected components. This may beaccomplished by using a deactivation element that includes, for example,isolated logic circuits, sets of instructions that may be executed bythe processor, and/or the like. In aspects of this implementation, forexample, all of the components of the IMD 600 depicted in FIG. 6 may becommunicatively coupled to the controller, which executes thedeactivation element 602 to logically disable selected components.

FIG. 7 is a schematic block diagram depicting an illustrative IMD 700having a deactivation element 702 capable of selectively disablingcomponents of the IMD 700, in accordance with embodiments of theinvention. The IMD 700 may include any number of different types of IMDssuch as for example, implantable sensors, implantable stimulators (e.g.,leadless cardiac pacing seeds), implantable control devices, and/or thelike. As shown in FIG. 7, the deactivation element 702 is a logicalmodule executable by a controller 704. For example, the deactivationelement 702 may include a set of computer-readable instructions that arestored in a memory 706 and that, when accessed from the memory 706 andexecuted by the controller 704, facilitate logically disabling any oneor more components of the IMD 700.

As shown in FIG. 7, a power source 708 (e.g., a battery) provides powerto the controller 704, a therapy circuit 710, a sensor circuit 712, thememory 706, an oscillator 714, and a communications component 716. Apower manager 718 may be configured to monitor the power source 708and/or one or more other components to detect an end-of-life (EOL)condition. As shown in FIG. 7, the therapy circuit 710 is coupled to anelectrode 720 and is configured to cause electrical pacing energy to bedischarged from the electrode 720. Similarly, the sensor circuit 712 iscoupled to a sensor 722, which, in embodiments, may be an electrode, apressure sensor, and optical sensor and/or the like. In embodiments, thetherapy circuit 710 may be coupled to more than one electrode 720. Inthe illustrated embodiment, the power manager 718 monitors componentssuch as the therapy circuit 710, the sensor circuit 712, and thecommunications component 716 by accessing information from thecontroller 704 corresponding to the operation of those components. Inembodiments, the power manager 718 may include a direct connection tothe components that it monitors.

The illustrative IMD 700 shown in FIG. 7 is not intended to suggest anylimitation as to the scope of use or functionality of embodiments of theinvention disclosed throughout this document. Neither should theillustrative IMD 700 be interpreted as having any dependency orrequirement related to any single component or combination of componentsillustrated therein. For example, in embodiments, the illustrative IMD700 may include additional components such as, for example, additionalsensor circuits (not illustrated). Additionally, any one or more of thecomponents depicted in FIG. 7 can be, in embodiments, integrated withvarious ones of the other components depicted therein (and/or componentsnot illustrated). Any number of other components or combinations ofcomponents can be integrated with the illustrative IMD 700 depicted inFIG. 6, all of which are considered to be within the scope of thisdisclosure.

In an example embodiment, the power manager 718 may monitor the therapycircuit 710 and detect an EOL condition. The EOL condition may include,for example, a condition in which the therapy circuit 710 is deliveringerratic or otherwise unexpected therapy. Upon detecting the EOLcondition, the power manager 718 may send a signal to the deactivationelement 702 to cause the deactivation element 702 to prevent power frombeing delivered from the power source 704 to the therapy circuit 710.The deactivation element 702 may continue to allow power to flow,however, to any number of the other components of the IMD 700. As thepower source 702 continues to deplete, the power manager 718 may detectanother EOL condition by detecting erratic or otherwise unexpectedbehavior by the communications component 716.

As shown in FIG. 7, the communications component 716 includes atransceiver 724 and an antenna 726. According to embodiments, thecommunications component 716 may include, instead of a transceiver, atransmitter, a receiver, or both. An EOL condition may be one in whichthe transceiver 724 (or transmitter) is not receiving sufficient powerto accurately modulate an outgoing signal, thereby causing errors and/orgaps in transmitted communication. Similarly, an EOL condition may beone in which the transceiver 724 (or receiver) is not receiving enoughpower to accurately demodulate an incoming signal, thereby causingerrors and/or gaps in received communication. Upon detecting the EOLcondition, the power manager 718 may send a signal to the deactivationelement 702 to cause the deactivation element 702 to prevent power frombeing delivered from the power source 708 to the communicationscomponent 716.

In embodiments, a power manager (e.g., the power manager 618 depicted inFIG. 6 or the power manager 718 depicted in FIG. 7) may be configured,as in the examples above, to selectively disable components of the IMDas EOL conditions are detected. In this manner, embodiments facilitatedisabling certain functions of an IMD with minimal disruption to otherfunctions. Additionally, in embodiments, sets of components (e.g., inputcircuits, output circuits, etc.) may be selectively disabled in stages,either electronically or logically. Disabling the IMD in stages may alsofacilitate allowing enough time for information to be stored,transmitted, or received. Various algorithms, processes, protocols, andthe like may be used to implement embodiments of a staged deactivation.FIG. 8 illustrates an example of such a process.

FIG. 8 is a flow diagram depicting an illustrative method 800 ofdeactivating an IMD in accordance with embodiments of the invention. Inthe illustrated example, the IMD may be, for example, a leadless pacingseed that includes at least a therapy circuit, a sensor circuit, and acommunications component. As shown in FIG. 8, the illustrative method800 includes detecting an end-of-life (EOL) condition (block 802). Inembodiments, a power manager (e.g., the power manager 618 depicted inFIG. 6 or the power manager 718 depicted in FIG. 7) may be configured todetect an EOL condition associated with the IMD by monitoring the powersource or one or more components that consume power from the powersource. Monitoring the power source, in embodiments, may include one ormore mechanisms and/or processes for monitoring power levels that arestored in, and/or are outputted from, the power source. Monitoring othercomponents, in embodiments, may include one or more mechanisms and/orprocesses for monitoring the functionality of those components toidentify erratic, unreliable, or otherwise unexpected behavior.

Embodiments of the illustrative method 800 further include preventingpower delivery to the therapy circuit (block 804). In response todetecting the EOL condition, the power manager may provide a signal to adeactivation element (e.g., the deactivation element 602 depicted inFIG. 6 or the deactivation element 702 depicted in FIG. 7) that causesthe deactivation element to prevent power from flowing from the powersource to the therapy circuit. In the illustrative method 800, whilecontinuing to monitor components of the IMD, the power manager detectsan insufficient power condition (e.g., another EOL condition) associatedwith the communications component. For example, the power manager maydetect that the communications component is communicating a number oferrors that exceed a threshold, is transmitting random packets, or thelike. In response to detecting the EOL condition, the power manager maysend a signal to the deactivation element to cause it to prevent powerdelivery to the communications component (block 808). During furthermonitoring, the power manager may detect an insufficient power conditionfor the sensor circuit (block 810) and, in response, may cause thedeactivation element to prevent power delivery to the sensor circuit(block 812). In embodiments, the order in which elements are deactivatedmay be different than the order described above. For example, inembodiments, the therapy circuit might be disabled last in order toprovide therapy to the patient for as long as possible.

FIG. 9 depicts another illustrative method 900 of deactivating an IMD inaccordance with embodiments of the invention. As shown in FIG. 9, theillustrative method 900 includes determining that an end-of-life (EOL)condition of the IMD is nearing (block 902) and setting an EOL statetrigger (block 904). According to embodiments, the EOL state trigger mayinclude a condition or conditions that, when satisfied, result in thedeactivation element deactivating the IMD. The condition may includepassage of a certain amount of time, a predetermined energy level in thepower source, an occurrence of a certain action (e.g., receipt of asignal from another IMD, a control device, or an external device), anon-occurrence of a certain action within a certain amount of time,and/or the like. In the illustrative method 900, the EOL state triggeris detected (block 906) and, in response, the IMD is disabled (block908).

As indicated previously, embodiments of the invention include an IMDsuch as a leadless pacing seed that operates within a system having oneor more additional leadless pacing seeds. Embodiments include modifyinga therapy program and/or communication structure of the remaining seedswhen a first seed reaches an end-of-life condition. In this manner, thesystem mitigates effects of the loss of the use of the first seed. FIG.10 is a block schematic diagram depicting illustrative operations of aleadless pacing system 1000 configured to mitigate for the loss of apacing seed, in accordance with embodiments of the invention. Accordingto various embodiments, the system 1000 depicted in FIG. 10 may includea system for providing cardiac resynchronization therapy (CRT),defibrillation therapy, and/or the like. Although the system 1000 isdescribed in the context of a cardiac stimulation system, the system1000 may represent any number of different types of systems such as, forexample, a neurostimulation system, an electrocardiograph sensingsystem, and/or the like.

The illustrative system 1000 includes a first leadless cardiac pacing(LCP) seed 1002, a second LCP seed 1004, and a control device 1006. Thefirst and second LCP seeds 1002 and 1004 may be any number of differenttypes of leadless pacing seeds. In embodiments, the seeds 1002 and 1004may be similar to the IMDs described previously such as, for example,the IMD 102 depicted in FIG. 1, the IMD 200 depicted in FIG. 2, and/orthe IMD 300 depicted in FIG. 3. The control device 1006 may be similarto the co-implanted device 202 depicted in FIG. 2 and may be, orinclude, a pacemaker module, a subcutaneous implantable cardioverterdefibrillator (S-ICD), and/or the like. The illustrated system 1000 alsoincludes an external device 1008 which may, in embodiments, be anexternal programmer, a magnet, an interrogation device, and/or the like.

The external device 1008 may be used to communicate with the implantablecontrol device 1006. For example, the external device 1008 may be usedto program such parameters as the timing of stimulation pulses inrelation to certain sensed electrical activity of the heart, the energylevel of stimulation pulses, the duration of stimulation pulses (thatis, pulse width), and/or the like. Additional information such aslocations of seeds 1002 and 1004 within heart chambers may beprogrammed, as well as pacing requirements involving one or more of thedistributed seeds 1002 and 1004. The external device 1008 may include anantenna to communicate with the control device 1006, using, for example,RF signals. The implantable control device 1006 may accordingly beequipped to communicate with the external device 1008 using, forexample, RF signals. Similarly, the control device 1006 may transmitinformation, such as sensed cardiac patient information, system statusinformation, warning information, and the like, to an external computingdevice. Physicians or care providers may then monitor the informationand make changes as appropriate.

According to embodiments of the system 1000 illustrated in FIG. 10, adual-chamber therapy may be provided using two LCP seeds 1002 and 1004,in which case each seed 1002 and 1004 may be reliant on the other'sbehavior. That is, for example, a first seed 1002 may be configured as a“slave” and may be configured to provide therapy in response to a secondseed 1004, configured as a “master,” providing therapy. In otherembodiments, the two LCP seeds 1002 and 1004 may be peer devices inwhich neither is a master or a slave, though aspects of the operation ofeach may depend upon aspects of the operation of the other. Inembodiments, the synchronization between the first and second seeds 1002and 1004 may be provided by communications between the two seeds 1002and 1004 themselves, by a control device 1008, and/or a combination ofthese. In other embodiments, a number of additional LCP seeds may beutilized for providing any number of different types of therapy such ascardaic resynchronization therapy, anti-tachycardia pacing therapy,neural stimulation therapy, and/or the like.

In embodiments, each of the first and second LCP seeds 1002 and 1004,operating according to a first operational state, may be monitored todetect an end-of-life (EOL) condition associated therewith. For example,each LCP seed 1002 and 1004 may include a power manager (e.g., the powermanager 216 depicted in FIG. 2) that monitors a battery and/or one ormore components (e.g., operational circuitry) of the seed 1002, 1004. Inembodiments, the control device 1006 and/or the external device 1008 maymonitor the LCP seeds 1002 and 1004 to detect EOL conditions. When oneof the LCP seeds 1002 or 1004 is placed into an EOL state, the other ofthe seeds 1002 or 1004 may be configured, as described herein, to adjustits therapy and/or communications so as to compensate for the loss ofthe functionality of the seed 1002 or 1004 that is in an EOL state. Inembodiments, the control device 1006 and/or the external device 1008 maybe used to facilitate modifying the therapy and/or communications. Inother embodiments, the seeds 1002 and 1004 themselves may be configuredto adjust operations to compensate for the loss of the other seed orseeds.

FIG. 10 also schematically illustrates an example of a compensationprocedure that may be implemented according to embodiments of theinvention. As shown in FIG. 10, when an EOL condition associated withthe first LCP seed 1002 is detected, a notification signal 1010 may betransmitted to the control device 1006 that indicates that the EOLcondition has been detected. The LCP seed 1002 may also transmitinformation 1012 to the control device 1006 to be used in modifyingtherapy programs and/or communication structures. Accordingly, theinformation 1012 may include, for example, operational parameters,communications protocols, physiological parameters sensed by the LCP1002, and/or the like.

Upon receiving the notification signal 1010 and the information 1012,the control device 1006 may, for example, implement a procedure forresynchronizing therapy and/or communication structures. In embodiments,the control device 1006 may include predetermined modified therapyprograms and/or communication structures, calculation modules fordetermining modified therapy programs and/or communication structures,and/or combinations of these. In the illustrated example, the controldevice 1006 may determine a modified therapy program that is configuredto facilitate providing therapy using only the second LCP seed 1004 anda modified communication structure that facilitates communicationsbetween the control device 1006 and only the second LCP seed 1004. Inother embodiments, the system 1000 may include a number of additionalLCP seeds and the control device 1006 may, for example, be configured todetermine a modified therapy program that redistributes therapy dutiesamong the remaining seeds.

The control device 1006 may provide the modified therapy program and/orcommunication structure via a communication 1014 to the second LCP seed1004. The LCP seed 1004 may store the modified therapy program and/orcommunication structure and configure its operational circuitry toimplement the modified program/structure, thereby implementing a secondoperational state. When the second LCP seed 1004 has finishedconfiguring itself to operate according to the second operational state,the second seed 1004 may provide a confirmation signal 1016 to thecontrol device 1006 to indicate to the control device that the secondseed 1004 is prepared to operate in the absence of operation of thefirst LCP seed 1002.

Having received the confirmation signal 1014, the control device 1006may provide an activation signal 1018 to the second LCP seed 1004 and adeactivation signal 1020 to the first LCP seed 1002. In embodiments, theactivation signal 1018 and the deactivation signal 1020 may be providedsubstantially simultaneously (e.g., in parallel), and, in embodiments,the two signals 1018 and 1020 may be provided sequentially (e.g., inseries). According to embodiments, the activation signal 1018 and thedeactivation signal 1020 may actually be communicated as a singlebroadcast communication. In aspects of such implementations, the controldevice 1006 may provide instructions to the first LCP seed 1002 thatconfigure the first LCP seed 1002 to interpret the broadcast signal as adeactivation signal, and instructions to the second LCP seed 1004 thatconfigure the second LCP seed 1004 to interpret the broadcast signal asan activation signal.

According to embodiments, the control device 1006 may provide any numberof various types of information to the external device 1008 regardingthe state of the system 1000. For example, in an embodiment, the controldevice 1006 may provide an indication to the external device 1008 thatthe control device 1006 has received the confirmation signal 1014 fromthe second LCP seed 1004. The external device 1008 may provideinstructions to the control device 1006 that cause the control device1006 to be configured to wait to receive an implementation signal fromthe external device 1008 before sending the activation signal 1018 anddeactivation signal 1020. In this manner, the system 1000 may beprepared to transition to a system state in which the first LCP seed1002 is disabled and the second LCP seed 1004 operates according to thesecond operational state. When the implementation signal is receivedfrom the external device 1008, the control device 1006 may provide theactivation signal 1018 and the deactivation signal 1020 to the secondLCP seed 1004 and the first LCP seed 1002, respectively. In embodiments,the implementation signal may be triggered by satisfaction of acondition, a manual input provided by a clinician, or the like.

Upon receiving the activation signal 1018, the second LCP seed 1004 mayprocess the signal 1018 and, in response, implement the secondoperational state. In this manner, the second LCP seed 1004 may beginproviding therapy according to the modified therapy program and maybegin communicating with the control device 1006 according to themodified communication structure. Upon receiving the deactivation signal1020, the first LCP seed 1002 may process the signal 1020, which maycause a deactivation element to disable the first LCP seed 1002. Asdiscussed above, the deactivation element of the first LCP seed 1002 maydisable the first LCP seed 1002 by logically disabling one or morecomponents thereof (e.g., a therapy circuit, a communications component,an oscillator, etc.), preventing power from being delivered to one ormore components (e.g., operational circuitry) thereof, blowing a fuse,crowbarring the power source, and/or the like. For example, inembodiments, the deactivation element of the first LCP seed 1002 mayinitially disable the therapy circuit, while leaving the communicationscomponent operational so that the first LCP seed 1002 can provide aconfirmation of deactivation (not shown) to the control device 1006. Inother embodiments, the deactivation element may disable the therapycircuit and the communications component.

In embodiments, the first and second LCP seeds 1002 and 1004 deliverpacing therapy in a dual-chamber pacing (DDD) mode in which the seed1002 is implanted such that at least one of its electrodes contactsatrial tissue and in which the seed 1004 is implanted such that at leastone of its electrodes contacts ventricular tissue. Upon the depletionof, for example, the power source of the seed 1002, the seed 1004 altersits therapy from pacing in a DDD mode to pacing in a ventricular pacing(VVI) mode. In another embodiment, the first and second LCP seeds 1002and 1004 deliver cardiac resynchronization therapy in which the seed1002 is implanted such that at least one of its electrodes contacts leftventricular tissue and in which the seed 1004 is implanted such that atleast one of its electrodes contacts right ventricular tissue. Upondepletion of, for example, the power source of the seed 1002, the seed1004 alters its therapy from cardiac resynchronization therapy tobradycardia therapy and paces in a right ventricular-only VVI mode.

FIG. 11 is a flow diagram depicting an illustrative method 1100 ofdeactivating a first IMD that is being replaced by a second IMD, inaccordance with embodiments of the invention. As shown in FIG. 11, theillustrative method 1100 includes detecting an end-of-life condition(EOL) of a first device (block 1102) and, in response, activating asecond device (block 1104). In embodiments, the second device may beimplanted before an EOL condition of the first device is anticipated andmay be initially in a dormant state. The dormant state may, for example,be characterized by a state in which the second device has only enoughcomponents activated so that the second device can receive a signal fromthe first device, from an external device, and/or the like.

Accordingly, the second device may be activated by a signal sent fromthe first device to the second device. Activation of the second devicemay place the second device in a stand-by state, in which the seconddevice can receive information and/or additional instructional signalsfrom the first device, a control device, an external device, and/or thelike. In embodiments, the second device may be activated by a signalsent from the control device or an external device.

In response to detecting the EOL condition of the first device, thefirst device transfers information to the second device (block 1106). Inembodiments, the information transferred to the second device mayinclude operational parameters such as therapy parameters, physiologicalparameters, and the like. The method 1100 further includes configuringthe second device to replace the therapy provided by the first device(block 1108). For example, the second device may process the informationreceived from the first device to generate a set of operationalparameters that may be used to implement an operational state in whichthe second device provides therapy in a manner that replaces the therapyprovided by the first device.

Once configured, the second device is activated, to begin operationaccording to the operational state (block 1110) and the first device isdisabled (block 1112). In embodiments, the second device may beactivated automatically upon receiving and processing the informationfrom the first device. In other embodiments, the second device may beactivated upon receiving an activation signal from a control deviceand/or an external device. Similarly, the first device may be disabledautomatically after sending the information to the second device or uponreceiving a confirmation signal from the second device, a controldevice, and/or an external device.

FIG. 12 is a flow diagram depicting an illustrative method 1200 ofdeactivating a leadless pacing seed that is part of a leadless pacingsystem, in accordance with embodiments of the invention. As shown inFIG. 12, the illustrative method 1200 includes detecting an end-of-life(EOL) condition of a first pacing seed (block 1202) and, in response,sending a signal to a control device that indicates the EOL condition ofthe first pacing seed (block 1204). In embodiments, the first pacingseed includes a power manager that monitors the power source and/or oneor more components (e.g., operational circuitry) of the seed to detectan EOL condition. Upon detecting the EOL condition, the power managermay cause a controller to communicate, via a communications component, asignal to a control device.

As illustrated in FIG. 12, the control device determines a modifiedtherapy program based on an anticipated loss of the first pacing seed(block 1206) and communicates the modified therapy program to a secondpacing seed (block 1208). According to various embodiments, the controldevice includes a processor that executes a set of routines to determinethe modified therapy program. In embodiments, the control device mayinclude a memory that stores a set of modified therapy program, and thecontrol device may select the appropriate program based on anidentification of the particular seed that has reached an EOL condition.A modified therapy program may include different sets of operationalparameters for each of a number of seeds, as described above withrespect to FIG. 11, and the control device may communicate each set ofoperational parameters to the appropriate seed.

In the illustrative method 1200, the control device also determines amodified seed communication structure based on the anticipated loss ofthe first pacing seed (block 1210) and communicates the modified seedcommunication structure to the second pacing seed (block 1212). Thismodified communication structure may specify communication flows,protocols, and/or the like.

In embodiments, prior to the anticipated loss of the first pacing seed(prior to block 1202) the second pacing seed operates in a low-powercommunication mode. The low-power communication mode limits the energyused for communication before the second seed is delivering therapy. Inorder to achieve the lower power in this mode, the second seed'scommunication components may, for example, operate at a lower receiveand/or transmit bit rate. After an EOL condition has been detected, thecommunication structure of the second seed may be modified to ahigher-power mode that can support the communication requirements of thesecond seed while it provides therapy.

As shown in FIG. 12, the control device sends a signal to the secondseed to cause the second seed to implement the modified therapy program(block 1214). In embodiments, the system may include a number ofadditional seeds to which the control device has provided modifiedtherapy programs and communication structures and the control device maysend each of these seeds a signal to cause implementation of theprograms and structures. In embodiments, for example, the control devicemay broadcast a signal that, when received by any of the seeds, causesthe seed to implement modified therapy programs and/or communicationstructures. The seeds may be configured to respond to the control devicewith a verification signal, indicating that the modified therapy programand communication structure have been implemented. Upon receiving theverification that the modified therapy program has been implemented(block 1216), the control device sends a signal to the first pacing seedto cause the first pacing seed to disable (block 1218). In embodiments,for example, the signal causes a deactivation element (e.g., asdescribed herein with reference to FIGS. 1-7) to disable one or morecomponents of the seed (e.g., a therapy circuit, a communicationscomponent, an oscillator, and/or the like). In embodiments, uponreceiving the signal to disable therapy (block 1218) the first pacingseed sends an acknowledge signal back to the control device. Aftertransmission of the acknowledge signal, the first pacing seed disablesitself as described herein with reference to FIGS. 1-7.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

We claim:
 1. An implantable medical device comprising: operationalcircuitry, wherein the operational circuitry comprises at least one of atherapy circuit and a sensor circuit; a communications module; a powersource configured to deliver energy to the operational circuitry; and adeactivation element configured to at least partially disable theoperational circuitry by interrupting delivery of energy from the powersource to the operational circuitry; a power manager configured todetect an end-of-life condition of the power source and, in response todetecting the end-of-life condition, cause the deactivation element toat least partially reversibly disable the operational circuitry.
 2. Theimplantable medical device of claim 1, wherein the implantable medicaldevice comprises a leadless cardiac pacing seed.
 3. The implantablemedical device of claim 1, wherein the operational circuitry comprisesthe therapy circuit.
 4. The implantable medical device of claim 3,wherein the deactivation element is configured to prevent energy frombeing delivered to the therapy circuit.
 5. The implantable medicaldevice of claim 1, further comprising a memory component configured tostore an indication of a post end-of-life state of the implantablemedical device.
 6. The implantable medical device of claim 5, whereinthe memory component comprises an active storage element.
 7. Theimplantable medical device of claim 6, wherein the power manager isconfigured to allow energy to be delivered to the memory componentduring the end-of-life state.
 8. The implantable medical device of claim5, wherein the memory component comprises a non-volatile memory element.9. The implantable medical device of claim 8, wherein the memorycomponent is further configured to store a plurality of operationalparameters during the end-of-life state.
 10. The implantable medicaldevice of claim 9, wherein the power source comprises a rechargeablebattery.
 11. The implantable medical device of claim 10, furthercomprising a controller, wherein the controller is configured to accessthe plurality of operational parameters in response to receiving anactivation signal.
 12. The implantable medical device of claim 11,wherein the controller is configured to restore the device to itspre-end-of-life state using the operational parameters.
 13. A leadlesscardiac pacing seed comprising: a therapy circuit; a communicationsmodule; a power source configured to deliver energy to the therapycircuit and the communications module; and a deactivation elementconfigured to disable at least one of the therapy circuit and thecommunications module by reversibly interrupting delivery of energy fromthe power source to the therapy circuit or the communications module; apower manager configured to detect an end-of-life condition of the seedand, in response to detecting the end-of-life condition, cause thedeactivation element to reversibly disable at least one of the therapycircuit and the communications module.
 14. The leadless cardiac pacingseed of claim 13, further comprising a memory component configured tostore an indication of an end-of-life state.
 15. The leadless cardiacpacing seed of claim 14, wherein the memory component comprises anactive storage element.
 16. The leadless cardiac pacing seed of claim15, wherein the power manager is configured to allow energy to bedelivered to the memory component during the end-of-life state.
 17. Theleadless cardiac pacing seed of claim 14, wherein the memory componentcomprises a non-volatile memory element.
 18. The leadless cardiac pacingseed of claim 17, wherein the memory component is further configured tostore a plurality of operational parameters during the end-of-lifestate, and wherein the controller is configured to access the pluralityof operational parameters in response to receiving an activation signal.19. The implantable medical device of claim 18, wherein the controlleris configured to restore the device to its pre-end-of-life state usingthe operational parameters.
 20. A cardiac pacing system comprising: animplantable leadless cardiac pacing seed configured to deliverelectrostimulation therapy to a patient, the implantable leadlesscardiac pacing seed comprising: a therapy circuit; a communicationsmodule configured to receive a deactivation signal from an externaldevice; a power source configured to deliver energy to the therapycircuit and the communications module; a power manager configured todetect an end-of-life condition of at least one of the power source andthe therapy circuit and, in response to detecting the end-of-lifecondition, place the implantable leadless cardiac pacing seed in anend-of-life state; a deactivation element configured to interruptdelivery of energy from the power source to the therapy circuit so as toreversibly disable the therapy circuit in response to the deactivationsignal being received by the communications module; and a memorycomponent configured to store an indication of an end-of-life state ofthe seed; and an external device configured to provide the deactivationsignal to the communications module.